This invention is directed to an audiovisual display system, and more particularly to a method for producing a three dimensional image and an audiovisual display system for displaying the three dimensional image.
Audiovisual display systems are well known in the art. Among the more sophisticated audiovisual display systems are miniaturized screens used in combination with film loop projectors which display a moving image on a small portable screen providing a portable movie theater. These systems are of a fairly simple construction having an image source and a miniaturized screen and therefore are portable. Because these audiovisual display systems are capable of displaying moving pictures they have become desirable for use with demonstration videos for educational purposes and point of sale demonstration in retail stores.
These types of audiovisual display systems suffer from the disadvantage that they are limited to two dimensional displays which severely reduce the realism and aesthetic value of the information displayed. Some films are produced with a process which allows for three dimensional viewing of the film being displayed on the audiovisual display system. However, this method suffers from the disadvantage that in order to view the film as three dimensional, the viewer is required to wear special glasses which are not always readily available, are uncomfortable, or distort portions of the picture.
Another prior art approach known as the holographic process overcomes this deficiency by providing a three dimensional object which may be viewed without the use of special viewing apparatus such as glasses. Holograms operate by diffracting light from a two dimensional interference pattern recorded on a light sensitive plate or film. When light shines on the light sensitive plate, a three dimensional image is displayed. Holograms do provide greater aesthetic value and hold the attention of the viewer due to their three dimensional appearance.
Holograms suffer from several disadvantages. First, holograms provide static images and do not lend themselves to producing images of complex movement. On a more technical level the diffraction angle of the light scattered by a holographic optical element is a function of wavelength. For this reason holographic optics must be designed for operation at a particular wavelength. As a result, holographs require complicated precise machinery to produce and view an image. Additionally, if holographic optics are to focus light precisely, the light must be monochromatic. Accordingly, holograms often appear to be tinged with the one color of the monochromatic laser so that ruby lasers provide a red tinge to the hologram, detracting from the realism. Lastly, diffraction efficiency is extremely important in producing holograms because only light diffracted by the hologram is focused to a desired point. High efficiencies are not always attainable and low diffraction efficiency results in both high losses and high levels of scattered light in the wrong place. Accordingly, it is desirable to provide an audiovisual display system which overcomes the deficiencies of the prior art by producing a three dimensional image utilizing a simplified structure.